diff --git a/src/database/mongo/hash.js b/src/database/mongo/hash.js
index 791cbc12cc..d887143d89 100644
--- a/src/database/mongo/hash.js
+++ b/src/database/mongo/hash.js
@@ -7,6 +7,9 @@ module.exports = function(db, module) {
 
 	module.setObject = function(key, data, callback) {
 		callback = callback || helpers.noop;
+		if (!key) {
+			return callback();
+		}
 		data._key = key;
 		db.collection('objects').update({_key:key}, {$set:data}, {upsert:true, w: 1}, function(err) {
 			callback(err);
@@ -21,10 +24,16 @@ module.exports = function(db, module) {
 	};
 
 	module.getObject = function(key, callback) {
-		db.collection('objects').findOne({_key:key}, {_id:0, _key:0}, callback);
+		if (!key) {
+			return callback();
+		}
+		db.collection('objects').findOne({_key: key}, {_id:0, _key:0}, callback);
 	};
 
 	module.getObjects = function(keys, callback) {
+		if (!Array.isArray(keys) || !keys.length) {
+			return callback();
+		}
 		db.collection('objects').find({_key: {$in: keys}}, {_id: 0}).toArray(function(err, data) {
 			if(err) {
 				return callback(err);
@@ -42,19 +51,52 @@ module.exports = function(db, module) {
 	};
 
 	module.getObjectField = function(key, field, callback) {
+		if (!key) {
+			return callback();
+		}
 		field = helpers.fieldToString(field);
-		module.getObjectFields(key, [field], function(err, data) {
-			callback(err, data ? data[field] : null);
+		var _fields = {
+			_id: 0
+		};
+		_fields[field] = 1;
+		db.collection('objects').findOne({_key: key}, _fields, function(err, item) {
+			if (err || !item) {
+				return callback(err, null);
+			}
+
+			callback(null, item[field] || null);
 		});
 	};
 
 	module.getObjectFields = function(key, fields, callback) {
-		module.getObjectsFields([key], fields, function(err, items) {
-			callback(err, items ? items[0] : null);
+		if (!key) {
+			return callback();
+		}
+		var _fields = {
+			_id: 0
+		};
+
+		for(var i=0; i<fields.length; ++i) {
+			fields[i] = helpers.fieldToString(fields[i]);
+			_fields[fields[i]] = 1;
+		}
+		db.collection('objects').findOne({_key: key}, _fields, function(err, item) {
+			if (err) {
+				return callback(err);
+			}
+			item = item || {};
+			var result = {};
+			for(i=0; i<fields.length; ++i) {
+				result[fields[i]] = item[fields[i]] || null;
+			}
+			callback(null, result);
 		});
 	};
 
 	module.getObjectsFields = function(keys, fields, callback) {
+		if (!Array.isArray(keys) || !keys.length) {
+			return callback(null, []);
+		}
 		var _fields = {
 			_id: 0,
 			_key: 1
@@ -80,10 +122,10 @@ module.exports = function(db, module) {
 				item;
 
 			for (var i=0; i<keys.length; ++i) {
-				var item = map[keys[i]] || {};
+				item = map[keys[i]] || {};
 
 				for (var k=0; k<fields.length; ++k) {
-					if (item[fields[k]] === null || item[fields[k]] === undefined) {
+					if (item[fields[k]] === undefined) {
 						item[fields[k]] = null;
 					}
 				}
@@ -117,20 +159,26 @@ module.exports = function(db, module) {
 	};
 
 	module.isObjectField = function(key, field, callback) {
+		if (!key) {
+			return callback();
+		}
 		var data = {};
 		field = helpers.fieldToString(field);
 		data[field] = '';
-		db.collection('objects').findOne({_key:key}, {fields:data}, function(err, item) {
+		db.collection('objects').findOne({_key: key}, {fields: data}, function(err, item) {
 			callback(err, !!item && item[field] !== undefined && item[field] !== null);
 		});
 	};
 
 	module.deleteObjectField = function(key, field, callback) {
 		callback = callback || helpers.noop;
+		if (!key) {
+			return callback();
+		}
 		var data = {};
 		field = helpers.fieldToString(field);
 		data[field] = '';
-		db.collection('objects').update({_key:key}, {$unset : data}, callback);
+		db.collection('objects').update({_key: key}, {$unset : data}, callback);
 	};
 
 	module.incrObjectField = function(key, field, callback) {
@@ -142,12 +190,15 @@ module.exports = function(db, module) {
 	};
 
 	module.incrObjectFieldBy = function(key, field, value, callback) {
-		callback = callback || function() {};
+		callback = callback || helpers.noop;
+		if (!key) {
+			return callback();
+		}
 		var data = {};
 		field = helpers.fieldToString(field);
 		data[field] = value;
 
-		db.collection('objects').findAndModify({_key:key}, {}, {$inc: data}, {new:true, upsert:true}, function(err, result) {
+		db.collection('objects').findAndModify({_key: key}, {}, {$inc: data}, {new:true, upsert:true}, function(err, result) {
 			callback(err, result ? result[field] : null);
 		});
 	};
diff --git a/src/database/mongo/list.js b/src/database/mongo/list.js
index 46c53bfffa..4395e568a4 100644
--- a/src/database/mongo/list.js
+++ b/src/database/mongo/list.js
@@ -4,7 +4,12 @@ module.exports = function(db, module) {
 	var helpers = module.helpers.mongo;
 
 	module.listPrepend = function(key, value, callback) {
-		callback = callback || function() {};
+		callback = callback || helpers.noop;
+
+		if (!key) {
+			return callback();
+		}
+
 		value = helpers.valueToString(value);
 
 		module.isObjectField(key, 'array', function(err, exists) {
@@ -22,12 +27,18 @@ module.exports = function(db, module) {
 
 	module.listAppend = function(key, value, callback) {
 		callback = callback || helpers.noop;
+		if (!key) {
+			return callback();
+		}
 		value = helpers.valueToString(value);
 		db.collection('objects').update({ _key: key }, { $push: { array: value } }, {upsert:true, w:1}, callback);
 	};
 
 	module.listRemoveLast = function(key, callback) {
-		callback = callback || function() {};
+		callback = callback || helpers.noop;
+		if (!key) {
+			return callback();
+		}
 		module.getListRange(key, -1, 0, function(err, value) {
 			if (err) {
 				return callback(err);
@@ -40,7 +51,10 @@ module.exports = function(db, module) {
 	};
 
 	module.listTrim = function(key, start, stop, callback) {
-		callback = callback || function() {};
+		callback = callback || helpers.noop;
+		if (!key) {
+			return callback();
+		}
 		module.getListRange(key, start, stop, function(err, value) {
 			if (err) {
 				return callback(err);
@@ -52,13 +66,18 @@ module.exports = function(db, module) {
 
 	module.listRemoveAll = function(key, value, callback) {
 		callback =  callback || helpers.noop;
+		if (!key) {
+			return callback();
+		}
 		value = helpers.valueToString(value);
 
 		db.collection('objects').update({_key: key }, { $pull: { array: value } }, callback);
 	};
 
 	module.getListRange = function(key, start, stop, callback) {
-
+		if (!key) {
+			return callback();
+		}
 		var skip = start,
 			limit = stop - start + 1,
 			splice = false;
diff --git a/src/database/mongo/main.js b/src/database/mongo/main.js
index d9a1b4a9be..4611ac7e11 100644
--- a/src/database/mongo/main.js
+++ b/src/database/mongo/main.js
@@ -68,32 +68,51 @@ module.exports = function(db, module) {
 	};
 
 	module.exists = function(key, callback) {
-		db.collection('objects').findOne({_key:key}, function(err, item) {
+		if (!key) {
+			return callback();
+		}
+		db.collection('objects').findOne({_key: key}, function(err, item) {
 			callback(err, item !== undefined && item !== null);
 		});
 	};
 
 	module.delete = function(key, callback) {
 		callback = callback || helpers.noop;
-		db.collection('objects').remove({_key:key}, callback);
+		if (!key) {
+			return callback();
+		}
+		db.collection('objects').remove({_key: key}, callback);
 	};
 
 	module.deleteAll = function(keys, callback) {
 		callback = callback || helpers.noop;
+		if (!Array.isArray(keys) || !keys.length) {
+			return callback();
+		}
 		db.collection('objects').remove({_key: {$in: keys}}, callback);
 	};
 
 	module.get = function(key, callback) {
+		if (!key) {
+			return callback();
+		}
 		module.getObjectField(key, 'value', callback);
 	};
 
 	module.set = function(key, value, callback) {
-		var data = {value:value};
+		callback = callback || helpers.noop;
+		if (!key) {
+			return callback();
+		}
+		var data = {value: value};
 		module.setObject(key, data, callback);
 	};
 
 	module.increment = function(key, callback) {
 		callback = callback || helpers.noop;
+		if (!key) {
+			return callback();
+		}
 		db.collection('objects').update({_key: key}, { $inc: { value: 1 } }, callback);
 	};
 
diff --git a/src/database/mongo/sets.js b/src/database/mongo/sets.js
index 795a2b45bb..d1b053ce26 100644
--- a/src/database/mongo/sets.js
+++ b/src/database/mongo/sets.js
@@ -94,16 +94,21 @@ module.exports = function(db, module) {
 		});
 	};
 
-
 	module.isSetMember = function(key, value, callback) {
+		if (!key) {
+			return callback();
+		}
 		value = helpers.valueToString(value);
 
-		db.collection('objects').findOne({_key:key, members: value}, {_id: 0, members: 0},function(err, item) {
+		db.collection('objects').findOne({_key: key, members: value}, {_id: 0, members: 0},function(err, item) {
 			callback(err, item !== null && item !== undefined);
 		});
 	};
 
 	module.isSetMembers = function(key, values, callback) {
+		if (!key) {
+			return callback();
+		}
 		for (var i=0; i<values.length; ++i) {
 			values[i] = helpers.valueToString(values[i]);
 		}
@@ -122,11 +127,13 @@ module.exports = function(db, module) {
 	};
 
 	module.isMemberOfSets = function(sets, value, callback) {
-
+		if (!Array.isArray(sets) || !sets.length) {
+			return callback();
+		}
 		value = helpers.valueToString(value);
 
 		db.collection('objects').find({_key: {$in : sets}, members: value}, {_id:0, members: 0}).toArray(function(err, result) {
-			if(err) {
+			if (err) {
 				return callback(err);
 			}
 
@@ -143,12 +150,18 @@ module.exports = function(db, module) {
 	};
 
 	module.getSetMembers = function(key, callback) {
+		if (!key) {
+			return callback();
+		}
 		db.collection('objects').findOne({_key: key}, {members: 1}, {_id: 0, _key: 0}, function(err, data) {
 			callback(err, data ? data.members : []);
 		});
 	};
 
 	module.getSetsMembers = function(keys, callback) {
+		if (!Array.isArray(keys) || !keys.length) {
+			return callback();
+		}
 		db.collection('objects').find({_key: {$in: keys}}, {_id: 0, _key: 1, members: 1}).toArray(function(err, data) {
 			if (err) {
 				return callback(err);
@@ -168,6 +181,9 @@ module.exports = function(db, module) {
 	};
 
 	module.setCount = function(key, callback) {
+		if (!key) {
+			return callback(null, 0);
+		}
 		db.collection('objects').findOne({_key: key}, {_id: 0}, function(err, data) {
 			return callback(err, data ? data.members.length : 0);
 		});
diff --git a/src/database/mongo/sorted.js b/src/database/mongo/sorted.js
index 78a8d629fe..1f95ba2448 100644
--- a/src/database/mongo/sorted.js
+++ b/src/database/mongo/sorted.js
@@ -7,6 +7,9 @@ module.exports = function(db, module) {
 
 	module.sortedSetAdd = function(key, score, value, callback) {
 		callback = callback || helpers.noop;
+		if (!key) {
+			return callback();
+		}
 		if (Array.isArray(score) && Array.isArray(value)) {
 			return sortedSetAddBulk(key, score, value, callback);
 		}
@@ -42,7 +45,9 @@ module.exports = function(db, module) {
 
 	module.sortedSetsAdd = function(keys, score, value, callback) {
 		callback = callback || helpers.noop;
-
+		if (!Array.isArray(keys) || !keys.length) {
+			return callback();
+		}
 		value = helpers.valueToString(value);
 		var data = {
 			score: parseInt(score, 10),
@@ -62,6 +67,9 @@ module.exports = function(db, module) {
 
 	module.sortedSetRemove = function(key, value, callback) {
 		callback = callback || helpers.noop;
+		if (!key) {
+			return callback();
+		}
 		if (!Array.isArray(value)) {
 			value = [value];
 		}
@@ -74,6 +82,9 @@ module.exports = function(db, module) {
 
 	module.sortedSetsRemove = function(keys, value, callback) {
 		callback = callback || helpers.noop;
+		if (!Array.isArray(keys) || !keys.length) {
+			return callback();
+		}
 		value = helpers.valueToString(value);
 
 		db.collection('objects').remove({_key: {$in: keys}, value: value}, callback);
@@ -81,12 +92,18 @@ module.exports = function(db, module) {
 
 	module.sortedSetsRemoveRangeByScore = function(keys, min, max, callback) {
 		callback = callback || helpers.noop;
+		if (!Array.isArray(keys) || !keys.length) {
+			return callback();
+		}
 		db.collection('objects').remove({_key: {$in: keys}, score: {$lte: max, $gte: min}}, function(err) {
 			callback(err);
 		});
 	};
 
 	function getSortedSetRange(key, start, stop, sort, withScores, callback) {
+		if (!key) {
+			return callback();
+		}
 		db.collection('objects').find({_key:key}, {fields: {_id: 0, value: 1, score: 1}})
 			.limit(stop - start + 1)
 			.skip(start)
@@ -127,6 +144,9 @@ module.exports = function(db, module) {
 	};
 
 	function getSortedSetRangeByScore(key, start, count, min, max, sort, callback) {
+		if (!key) {
+			return callback();
+		}
 		if(parseInt(count, 10) === -1) {
 			count = 0;
 		}
@@ -157,19 +177,28 @@ module.exports = function(db, module) {
 	}
 
 	module.sortedSetCount = function(key, min, max, callback) {
-		db.collection('objects').count({_key:key, score: {$gte:min, $lte:max}}, function(err, count) {
+		if (!key) {
+			return callback();
+		}
+		db.collection('objects').count({_key: key, score: {$gte: min, $lte: max}}, function(err, count) {
 			callback(err, count ? count : 0);
 		});
 	};
 
 	module.sortedSetCard = function(key, callback) {
-		db.collection('objects').count({_key:key}, function(err, count) {
+		if (!key) {
+			return callback();
+		}
+		db.collection('objects').count({_key: key}, function(err, count) {
 			count = parseInt(count, 10);
 			callback(err, count ? count : 0);
 		});
 	};
 
 	module.sortedSetsCard = function(keys, callback) {
+		if (!Array.isArray(keys) || !keys.length) {
+			return callback();
+		}
 		var pipeline = [
 			{ $match : { _key : { $in: keys } } } ,
 			{ $group: { _id: {_key: '$_key'}, count: { $sum: 1 } } },
@@ -207,6 +236,9 @@ module.exports = function(db, module) {
 	};
 
 	function getSortedSetRank(method, key, value, callback) {
+		if (!key) {
+			return callback();
+		}
 		value = helpers.valueToString(value);
 		method(key, 0, -1, function(err, result) {
 			if(err) {
@@ -219,6 +251,9 @@ module.exports = function(db, module) {
 	}
 
 	module.sortedSetsRanks = function(keys, values, callback) {
+		if (!Array.isArray(keys) || !keys.length) {
+			return callback(null, []);
+		}
 		var data = new Array(values.length);
 		for (var i=0; i<values.length; ++i) {
 			data[i] = {key: keys[i], value: values[i]};
@@ -230,13 +265,19 @@ module.exports = function(db, module) {
 	};
 
 	module.sortedSetScore = function(key, value, callback) {
+		if (!key) {
+			return callback();
+		}
 		value = helpers.valueToString(value);
-		db.collection('objects').findOne({_key:key, value: value}, {fields:{score:1}}, function(err, result) {
+		db.collection('objects').findOne({_key:key, value: value}, {fields:{score: 1}}, function(err, result) {
 			callback(err, result ? result.score : null);
 		});
 	};
 
 	module.sortedSetsScore = function(keys, value, callback) {
+		if (!Array.isArray(keys) || !keys.length) {
+			return callback();
+		}
 		value = helpers.valueToString(value);
 		db.collection('objects').find({_key:{$in:keys}, value: value}).toArray(function(err, result) {
 			if (err) {
@@ -257,6 +298,9 @@ module.exports = function(db, module) {
 	};
 
 	module.sortedSetScores = function(key, values, callback) {
+		if (!key) {
+			return callback();
+		}
 		values = values.map(helpers.valueToString);
 		db.collection('objects').find({_key: key, value: {$in: values}}).toArray(function(err, result) {
 			if (err) {
@@ -287,6 +331,9 @@ module.exports = function(db, module) {
 	};
 
 	module.isSortedSetMembers = function(key, values, callback) {
+		if (!key) {
+			return callback();
+		}
 		values = values.map(helpers.valueToString);
 		db.collection('objects').find({_key: key, value: {$in: values}}).toArray(function(err, results) {
 			if (err) {
@@ -313,6 +360,9 @@ module.exports = function(db, module) {
 	};
 
 	function getSortedSetUnion(sets, sort, start, stop, callback) {
+		if (!Array.isArray(sets) || !sets.length) {
+			return callback();
+		}
 		var limit = stop - start + 1;
 		if (limit <= 0) {
 			limit = 0;
diff --git a/src/posts.js b/src/posts.js
index 4f9bbf9488..1cb277fabb 100644
--- a/src/posts.js
+++ b/src/posts.js
@@ -527,6 +527,9 @@ var async = require('async'),
 	};
 
 	Posts.getPostIndices = function(posts, uid, callback) {
+		if (!Array.isArray(posts) || !posts.length) {
+			return callback(null, []);
+		}
 		user.getSettings(uid, function(err, settings) {
 			if (err) {
 				return callback(err);